Plano-fresnel led lens and led assembly thereof

ABSTRACT

A plano-Fresnel LED lens and a LED assembly thereof are revealed. The lens is a Fresnel lens whose optical surface on the forward side thereof is a plano surface having saw teeth with vertical taper (draft with vertical shape) so that the lens in the LED assembly concentrates light emitted from a LED chip to generate light whose peak intensity is an elliptic distribution pattern. Moreover, the lens and the LED assembly thereof satisfy certain conditions. Thereby, light from the LED chip is gathered by a single lens to form a preset specific distribution pattern and is satisfying requirement of the ratio of the luminous flux that is larger than 85%. The plano-Fresnel LED lens and a LED assembly thereof are applied to lights and flashlights in mobile phones or cameras.

BACKGROUND OF THE INVENTION

The present invention relates to a LED lens and a LED assembly thereof,especially to a Plano-Fresnel LED lens whose peak intensity is anelliptic distribution pattern in a LED assembly, being applied to LEDlighting devices, flashlights of mobile phones or cameras.

LED with features of low voltage, low power consumption and longoperation life has been broadly applied to indicators, illuminators andso on. Moreover, due to pure light color, compact volume and flatpackage, LED is also used on flashlight of mobile phones. Yet lightemitted from LED chip is a point source with uneven brightness. Thus alot of studies focus on light collection. Besides minimization of chipsize, improvement of light emitting efficiency, the lens used is also animportant direction of technical development.

Along with development of modern technology, electronics are gettingmore miniature, compact and multi-functional. A lot of electronicproducts such as digital still cameras, PC cameras, network cameras,mobile phones and even personal digital assistant (PDA) are equippedwith a lens. The LED lights or flashlight applied to such products areformed by a single or multiple LED array(s). For convenience of easycarrying and humanized design, LED flashlights or lighting devices notonly meet requirements of luminous flux such as combinations of LEDelements with different distribution patterns but also require miniatureand lower cost.

In lens design of LED, there are two types-primary optical lens andsecondary optical lens. The primary optical lens is a lens directlypackaged on the LED chip and is for concentrating light while thesecondary optical lens is an LED array formed by signal chip or aplurality of LED chips for spreading light beams. The conventionaldesign of the primary optical lens is shown in ES2157829, symmetricalaspherical lens is used. Refer to JP3032069, JP2002-111068,JP2005-203499, US2006/187653, and CN101013193, spherical lens is used asprimary optical lens.

In JP2002-221658, spherical lens is applied to Bulk-type LED. Inhigh-level applications, the primary optical lens not only concentrateslight but also generates specific distribution pattern with even peakintensity such as large angle, small angle, round or ellipticdistribution pattern. The primary optical lens is used in combinationwith the LED array so as to achieve optimal optical effects.

The application of the primary optical lens is shown in FIG. 1A & FIG.1B. A lens 23 is covered over a LED chip 21. Light emitted from the LEDchip 21 passes through the lens 23 to be concentrated to form a presetlight pattern. Or a layer of secondary optical lens is added over theprimary optical lens for brightness uniformity. There are variousdesigns of the primary optical lens and some of them use a Fresneloptical surface, as revealed in WO/2003/083943, JP2005-049367, U.S. Pat.No. 6,726,859, US2007/0275344, US2008/0158854, EP1091167, andTW200711186 etc.

However, above conventional technique uses Fresnel lens covered over aplurality of LEDs, working as a secondary optical lens like a projector.Due to fast development of LED light emitting efficiency, theapplications of a single LED have become more important. In the LEDarray or light sources formed by a plurality of LEDs, the brightnessbecome in uniformity due to compensation of cross light beams throughthe lens. As to the single LED, the design of the primary optical lensis more complicated than that of the LED array or light sources loformed by multiple LEDs because both the light concentration efficiencyand the uniformity of brightness of the primary optical lens should beconsidered. A set of Fresnel zone plates is disposed on surface of theFresnel lens and a zone pitch thereof is increasing gradually from theinside to the outside or from the outside to the inside. Besides lightguiding and light collection, the Fresnel lens with features of lightweight, compact volume and plastic nature and lower cost is suitable forbeing applied to lighting systems. For example, in JP2005-257953 and US2006/0027828, a Fresnel lens with a single-side or double-side isdisposed over a LED light source so as to generate uniform brightness,as shown in FIG. 1A & FIG. 1B. Refer to TW560085, by a paraboloidsurface and a Fresnel lens, reducing the divergent light and uniformbrightness may be formed. Furthermore, refer to Korean 1020070096368 andTW 1261654, a LED primary lens is made by a Fresnel lens but thedistribution pattern thereof is a round distribution pattern.

However, as to multiple point LED lighting systems, brightnessuniformity of both illuminance and light intensity should be considered.Conventional techniques usually use a certain ratio of the zone pitch tothe zone height or changing zone pitch with changing zone height. Forlighting system formed by a plurality of LEDs, changing zone pitch isbetter for matching requirements of uniform illuminance/light intensity.As to a single LED primary optical lens, the zone pitch depends onoptical properties of the lens. Although the Fresnel lens withcomplicated surface and higher manufacturing cost, it provides betterlight efficiency and brightness uniformity, especially being applied tolighting devices with a single LED. In order to make light from singleLED achieve higher efficiency, the present invention provide a primaryoptical lens of the LED made by Fresnel lens so as to concentrate lightfrom surface of the LED chip and generate an elliptic distributionpattern with uniform peak intensity.

SUMMARY OF THE INVENTION

Therefore it is a primary object of the present invention to provide aplano-Fresnel LED lens and a LED assembly thereof. The LED assemblyhaving a LED chip for emitting light, a Fresnel lens fort concentratinglight and generating Elliptic distribution pattern with uniform peakintensity and a gel layer filled between the Fresnel lens and the LEDchip for sealing. Wherein, the Fresnel lens can be a plano-concave lenswhose outer surface is tapered or perpendicular. A concave surface ofthe Fresnel lens is an optical surface facing the light source and isable to be aspherical or spherical while a plano-Fresnel surface thereofis an optical surface on forward side and is a Fresnel optical surface.Moreover, the light-collecting curved surface (RF) for forming theplano-Fresnel surface can be aspherical or spherical surface and itszone can be draft with vertical shape and equal zone pitch andsatisfying the following conditions:

$\begin{matrix}{0.7 \leq \frac{f_{s}}{r_{n}} \leq 2.2} & (1) \\{0.1 \leq {\left( {N_{d\; 2} - 1} \right)\frac{d_{2}}{f_{s}}} \leq 1.25} & (2) \\{{\sqrt{\left( \frac{\varphi_{x} - \omega_{x}}{\pi} \right)^{2} + \left( \frac{\varphi_{y} - \omega_{y}}{\pi} \right)^{2}} \cdot f_{g}} \leq 0.6} & (3)\end{matrix}$

wherein:

$\begin{matrix}{f_{g} = {{\left( {\frac{1}{R_{1}} - \frac{1}{R_{F}}} \right) \cdot f_{s}}}} & (4) \\{\omega_{x} = {\tan^{- 1}\left( \frac{D}{{d\; 0} + {d\; 1} + {d\; 2} + {Lx}} \right)}} & (5) \\{\omega_{y} = {\tan^{- 1}\left( \frac{D}{{d\; 0} + {d\; 1} + {d\; 2} + {Ly}} \right)}} & (6)\end{matrix}$

Wherein f_(s) is effective focal length of the lens, r_(n) is radius ofa last zone of a Fresnel optical surface R2, d₂ is thickness of the lenson a central axis Z, N_(d2) is refractive index of the lens, 2φ_(x)(deg.) is an angle of a half of highest light intensity (I_(1/2)) in theX direction of the light emitted from the lens, 2φ_(y) (deg.) is anangle of a half of highest light intensity (I_(1/2)) in the Y directionof the light emitted from the lens, 2Lx is length of the LED chip in theX direction, 2Ly is length of the LED chip in the Y direction, fg is arelative focal length of the lens, R₁ is a radius of an optical surfaceon the source side, R_(F) is a radius of a plano-Fresnel surface on theforward side, d₀ is thickness of the LED chip, d₁ is thickness of a gellayer on the central axis, D is radius of an optical surface on theforward side.

Moreover, in order to meet various requirements of distribution patternand light concentration properties, the radius R_(F) of thelight-collecting curved surface (R_(F)) (a convex surface) for formingthe plano-Fresnel surface of the Fresnel lens can be set as a radius ofa spherical surface or an aspherical surface.

In order to simplify the manufacturing of the device, the plano-concaveFresnel lens can be replaced to be a plano-plano lens made from opticalmaterial whose forward-side optical surface is a plano-Fresnel surfaceand is satisfying from equation (1) to equation (3). Where the opticalmaterial may be selected by plastic resin or glass.

In order to improvement concentrating efficiency of LED assembly, theouter surface of the Fresnel lens may be tapered with taper v whoseforward-side optical surface is a Fresnel convex surface and issatisfying from equation (1) to equation (3).

It is another object of the present invention to provide a LED assemblythat includes a plano-concave or a plano-plano Fresnel LED lens and aLED chip and the LED assembly features on its elliptic distributionpattern and the ratio of luminous flux is larger than 85% (η=β/α≧85% )and is satisfying the following conditions:

E _(1/2)≦0.6E _(d)   (7)

wherein

$\begin{matrix}{E_{1/2} = {\frac{I_{1/2}}{\left( {\pi \; {r_{n} \cdot \sin}\; \varphi_{x}} \right) \cdot \left( {{r_{n} \cdot \sin}\; \varphi_{y}} \right)} \cdot \eta}} & (8)\end{matrix}$

wherein r_(n) is radius of a last zone of the Fresnel surface R2, α isluminous flux of the LED chip, β is luminous flux at infinity (100×f_(s)) of the forward side without consideration of attenuation, η isratio of the luminous flux, E_(d) is incidence of the LED chip, andE_(1/2) is incidence at the half of highest light intensity from theFresnel lens surface.

The plano-Fresnel LED lens and the LED assembly thereof according to thepresent invention have elliptic distribution pattern and satisfies therequirement of luminous flux larger than 85%. Moreover, the thickness ofthe lens is minimized so that the lens can be applied to a single LED,LED arrays for lighting, or flashlights on mobile phones and cameras.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows LED assembly of a conventional LED lens;

FIG. 1B shows LED assembly of a conventional LED lens;

FIG. 2 is a perspective view of LED assembly of a Fresnel LED lenswithout taper according to the present invention;

FIG. 3 is a perspective view of LED assembly of a Fresnel LED lens withtaper according to the present invention;

FIG. 4 shows a relationship between the radius of a convex surface and aplano-Fresnel surface of a Fresnel LED lens having draft with verticalshape and equal zone pitch;

FIG. 5 shows a relationship between the radius of a convex surface and aplano-Fresnel surface of a Fresnel LED lens having draft with verticalshape and equal zone height;

FIG. 6 is a schematic drawing showing LED assembly of an embodimentaccording to the present invention;

FIG. 7 is a schematic drawing showing taper of a Fresnel LED lens of anembodiment according to the present invention;

FIG. 8 shows light paths of LED assembly of an embodiment according tothe present invention;

FIG. 9 shows refraction of group A light beams and group B light beamsby a Fresnel LED lens;

FIG. 10 shows light path of group A light beams and group B light beamspassing through a Fresnel LED lens;

FIG. 11 is a schematic drawing uniform light intensity formed bycombination of group A light beams with group B light beams in FIG. 9 &FIG. 10;

FIG. 12 shows relationship between light intensity distribution of thefirst embodiment of the LED assembly and grazing angle in a polarcoordinate system light;

FIG. 13 shows relationship between light intensity distribution of thesecond embodiment of the LED assembly and grazing angle in a polarcoordinate system light;

FIG. 14 shows relationship between light intensity distribution of thethird embodiment of the LED assembly and grazing angle in a polarcoordinate system light;

FIG. 15 shows relationship between light intensity distribution of thefourth embodiment of the LED assembly and grazing angle in a polarcoordinate system light;

FIG. 16 shows relationship between light intensity distribution of lothe fifth embodiment of the LED assembly and grazing angle in a polarcoordinate system light;

FIG. 17 shows relationship between light intensity distribution of thesixth embodiment of the LED assembly and grazing angle in a polarcoordinate system light;

FIG. 18 shows relationship between light intensity distribution of theseventh embodiment of the LED assembly and grazing angle in a polarcoordinate system light;

FIG. 19 shows relationship between light intensity distribution of theeighth embodiment of the LED assembly and grazing angle in a polarcoordinate system light;

FIG. 20 shows relationship between light intensity distribution of theninth embodiment of the LED assembly and grazing angle in a polarcoordinate system light;

FIG. 21 shows relationship between light intensity distribution of thetenth embodiment of the LED assembly and grazing angle in a polarcoordinate system light;

FIG. 22 shows relationship between light intensity distribution of theeleventh embodiment of the LED assembly and grazing angle in a polarcoordinate system light;

FIG. 23 shows relationship between light intensity distribution of thetwelfth embodiment of the LED assembly and grazing angle in a polarcoordinate system light; and

FIG. 24 shows relationship between light intensity distribution of thethirteenth embodiment of the LED assembly and grazing angle in a polarcoordinate system light.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Refer to FIG. 6, a LED assembly 10 according to the present inventioncomprises a LED chip 11, a gel layer 12 and a lens 13 along a centralaxis Z from a source side to a forward side. When light is emitted fromthe LED chip 11, passing through the gel layer 12 and being concentratedby the lens 13 to form a light beam with elliptic distribution patternsymmetrical to the central axis Z that projects onto the forward side.The lens 13 is made of optical material such as optical glass or opticalplastic resin. A concave surface of the lens 13 is a source-side opticalsurface R1 facing on the light source and is aspherical or sphericaloptical surface. The other side opposite to the concave surface is aplano-Fresnel optical surface R2 with draft with vertical shape andfacing on the forward side. The plano-Fresnel optical surface R2, thelens thickness d₂ and the effective focal length f_(s) of the lens 13satisfy the equation (1) and the equation (2). The angle 2φ (having2φ_(x) in the X direction and 2φ_(y) in the Y direction) of distributionpattern of light intensity formed by the lens 13 satisfies the equation(3).

The material of the gel layer 12 is not restricted. In the LED assembly,optical resin or silicon gel is commonly used.

Refer to FIG. 2, the LED assembly 10 is a plano-Fresnel LED lens 13. Anoptical surface R1 of the lens 13 on source side is a flat surface(R1=∞) while the other optical surface R2 (opposite surface) on forwardside is a plano-Fresnel optical surface with vertical shape draft.

Refer to FIG. 3, a further embodiment of the LED assembly 20 isrevealed. Along with the central axis Z from the source side to theforward side, the LED assembly 20 comprises of a LED chip 21, a gellayer 22 and a plano-Fresnel lens 23. The difference between this LEDassembly 20 and the LED assembly 10 in FIG. 2 is in that an outersurface of the lens 23 is with taper v, as shown in FIG. 7 so as toreduce divergent from the side surface of the lens 23 and improve theoptical efficiency.

The forward-side optical surface R2 of the lens 13 or the lens 23 of theinvention is a plano-Fresnel optical surface having draft with verticalshape, as shown in FIG. 4 & FIG. 5. The Fresnel optical surface R2 istransformed by the radius of R_(F). By means of different ways oftransformation the radius of R_(F), various Fresnel optical surface R2are formed, as equal zone pitch (FIG. 4) and equal zone height (FIG. 5).

Refer to FIG. 4, a plano-Fresnel optical surface R2 with equal zonepitch is shown. The zone pitch r_(t) thereof is a fixed value. The lightoptical surface with radius of R_(F) is transformed into a multi-zoneplano-Fresnel optical surface R2 by equal zone pitch r_(t) but withunequal zone height h_(d) (FIG. 6). Refer to FIG. 5, a plano-Fresneloptical surface R2 with equal zone height is shown. That means the zoneheight h_(d) is a fixed value. The optical surface with radius of R_(F)is transformed into a multi-zone Fresnel optical surface R2 by equalvertical zone height h_(d) but with unequal zone pitch r_(t).

Each zone on the forward-side plano-Fresnel optical surface R2 is formedby a slope and a vertical zone surface (ring-shaped surface) so that thezone is called draft with vertical shape. The radius of the first zoneis r, and the radius of the last zone is r_(n). As shown in FIG. 9, whenlight emits into the plano-Fresnel optical surface R2, the light isrefracted by the slope of each zone so as to achieve similar opticaleffects of paraboloid optical surface.

Refer from FIG. 9 to FIG. 11, after being refracted by the Fresneloptical surface R2, the angles of emergence φ of the group A light beams(such as A1, A2, A3 light beam) on an object are different due todifferent incident angles of the light beams A1, A2, A3, as shown inFIG. 10. On the position parallel to the central axis toward verticaldirection, the group A light beams have higher light intensity in thecenter thereof. Similarly, after being refracted by the plano-Fresneloptical surface, a light-beam group B (such as B1, B2, B3 light beam) isalso a light-beam group whose light intensity is higher in the centerthereof. By the combinations of group A and group B, as shown in FIG.11, a light pattern with even light intensity is generated so as toimprove brightness uniformity.

If the optical surface R1 of the lens 13 or the lens 23 is formed byaspherical optical surface, the Aspherical Surface Formula is theequation (9):

$\begin{matrix}{Z = {\frac{{ch}^{2}}{1 + \sqrt{\left( {1 - {\left( {1 + K} \right)c^{2}h^{2}}} \right)}} + {A_{4}h^{4}} + {A_{6}h^{6}} + {A_{8}h^{8}} + {A_{10}h^{10}}}} & (9)\end{matrix}$

wherein c is curvature, h is height of the lens, K is conic constant,and A₄ to A₁₀ respectively are Nth Order Aspherical Coefficients.

The curvature radius of R_(F) of the plano-Fresnel optical surface R2 isalso defined by the equation (9), wherein Conic Constant of thecurvature radius R_(F) of the paraboloid for collecting light is −1(K=−1) for paraboloid surface, is 0 (K=0) for spherical surface,respectively.

Refer to FIG. 8, light from the LED chip 11 (21) is concentrated andrefracted by the lens 13 (23) to form a required elliptic distributionpattern that satisfies the condition of β/α≧85% at an angle of 2φ(2φ_(x) in the X direction and 2φ_(y) in the Y direction). Neglectingattenuation such as air refraction and scattering, the equation (7) issatisfied. Therefore, by a plano-concave or plano-plano Fresnel LED lensand a LED chip, the LED assembly 10 (20) can emit preset Ellipticdistribution pattern with uniform light intensity. Moreover, the LEDassembly can be used in the form of a single assembly or an array formedby the LED assemblies with different distribution patterns.

In an embodiment of the present invention, the LED chip 11 is a blu-raywhose size is 1.85×0.77 mm, 1st peak wave-length is 450 nm, and 2nd peakwave-length is 550 nm. The blue light has diverge angle of ω_(x)=39.8°in the X direction and ω_(y)=35.2° in the Y direction for last lightbeam, α=78.5 lm, and light intensity E_(d)=23.97 Lux. The diameter ofthe lens 13(23) is 5 mm (D=2.5mm). The optical surface on the forwardside R2 is a Fresnel optical surface having vertical shape, and equalzone height/or equal zone pitch. The gel layer 12 is made fromtransparent optical silicon gel with refractive index of 1.491. As tothe LED assembly with a primary optical lens, other components exceptthe lens and LED assembly of the present invention are obvious to thosein the art. Thus the size and material of the components, wavelength andemitting angle of LED, patterns, the zone pitch and the zone height ofthe Fresnel optical surfaces all can be changed, modified and evensubstituted with equal effect parts.

As to the following thirteen embodiments, in the first to seventhembodiments, a LED assembly with a plano-plano Fresnel lens that is withno taper and equal zone height is used. In the eighth and ninthembodiments, a LED assembly with a plano-plano Fresnel lens that is withtaper and equal zone height is used. In the tenth and eleventhembodiments, a LED assembly with a plano-plano Fresnel lens that is withno taper and equal zone pitch is used. In the twelfth and thirteenthembodiments, a LED assembly with a plano-concave Fresnel lens that iswith no taper and equal zone height is used.

Two tables are shown in the following each embodiment respectively,wherein the first table includes data of curvature radius R (unit:mm) ofthe source-side optical surface R1 as well as that of the opticalsurface on the source side R2, or curvature radius R_(F) (unit:mm),along a central axis Z from the source side to the forward side, theon-axis surface spacing di (unit:mm), the taper ν of the lens (13˜23),respective refractive index (N_(d)) and the optical surface number.Denoted that labeled with * is an aspherical Fresnel optical surface.The second table is shown the respective parameters in the equation (9)of the aspherical Fresnel optical surface, radius r₁ of a first Fresnelzone from the center of the lens, radius r_(n) of the last Fresnel zone,Fresnel zone height h_(d) and number of Fresnel zones.

The First Embodiment

Refer to FIG. 6, FIG. 12.

TABLE ONE fs = 2.024 υ = 0 Surface No. R or R_(F) d_(i) N_(di) S0 ∞ 0.10S1 ∞ 0.52 1.410 S2* 1.000 2.00 1.582 *Aspherical Zone Fesnel

TABLE TWO K A₂ A₄ A₆ Aspherical −1.0000E+00 0.0000E+00 0.0000E+000.0000E+00 Surface h_(d) r₁ r_(n) No. of Zone Fesnel Surface 0.1 0.4472.490 31 (mm)

In this embodiment, the lens 13 is made from glass with refractive indexNd2 of 1.582 and Abbe number vd2 of 61.7. The light is concentrated bythe lens 13 to form an elliptic distribution pattern, 68° in the Xdirection, 30° in the Y direction and the luminous flux β=69.201 lm atinfinity (100× f_(s)) without consideration of air refraction andscattering. The following values satisfy the equation (1), equation (2),equation (3) and equation (7):

η = 0.8815 I_(1/2) = 33.5 φ_(x) = 32.5 φ_(y) = 15.2$\frac{f_{s}}{r_{n}} = 0.8130$${\left( {N_{d\; 2} - 1} \right)\frac{d_{2}}{f_{s}}} = 0.5751$${\sqrt{\left( \frac{\varphi_{x} - \omega_{x}}{\pi} \right)^{2} + \left( \frac{\varphi_{y} - \omega_{y}}{\pi} \right)^{2}} \cdot f_{g}} = 0.2394$$\frac{E_{1/2}}{E_{d}} = 0.4489$

By the above table one and table two as well as FIG. 12, it has beenproved that the LED assembly with plano-Fresnel LED lens of theinvention can achieve higher efficiency and generate an ellipticdistribution pattern with uniform peak intensity so as to increase theapplication of the invention.

The Second Embodiment

Refer to FIG. 6 & FIG. 13.

TABLE THREE f = 2.530 υ = 0 Surface No. R or R_(F) d_(i) Nd_(i) S0 ∞0.10 S1 ∞ 0.52 1.410 S2* 1.250 2.00 1.582 *Aspherical Zone Fesnel

TABLE FOUR K A₂ A₄ A₆ Aspherical −8.5000E−01 0.0000E+00 2.4000E−055.7000E−08 Surface h_(d) r₁ r_(n) No. of Zone Fesnel Surface 0.1 0.4992.480 30 (mm)

In this embodiment, the lens 13 is made from glass with refractive indexN_(d2) of 1.582 and Abbe number V_(d2) of 61.7. The light isconcentrated by the lens 13 to form an elliptic distribution pattern,68° in the X direction, 33° in the Y direction and the luminous fluxβ=70.245 lm at infinity (100× f_(s)) without consideration of airrefraction and scattering. The following values satisfy the equation(1), equation (2), equation (3) and equation (7):

η = 0.8948 I_(1/2) = 32.5 φ_(x) = 33.7 φ_(y) = 16.8$\frac{f_{s}}{r_{n}} = 1.0203$${\left( {N_{d\; 2} - 1} \right)\frac{d_{2}}{f_{s}}} = 1.1410$${\sqrt{\left( \frac{\varphi_{x} - \omega_{x}}{\pi} \right)^{2} + \left( \frac{\varphi_{y} - \omega_{y}}{\pi} \right)^{2}} \cdot f_{g}} = 0.1319$$\frac{E_{1/2}}{E_{d}} = 0.3915$

By the above table three and table four as well as FIG. 13, it has beenproved that the LED assembly with plano-Fresnel LED lens of theinvention can achieve higher efficiency and generate an ellipticdistribution pattern with uniform peak intensity so as to increase theapplication of the invention.

The Third Embodiment

Refer to FIG. 6 & FIG. 14.

TABLE FIVE fs = 2.530 υ = 0 Surface No. R or R_(F) d_(i) N_(di) S0 ∞0.10 S1 ∞ 0.52 1.410 S2* 1.250 2.00 1.582 *Aspherical Zone Fesnel

TABLE SIX K A₂ A₄ A₆ Aspherical −1.0000E+00 0.0000E+00 0.0000E+000.0000E+00 Surface h_(d) r₁ r_(n) No. of Zone Fesnel Surface 0.06 0.3872.510 42 (mm)

In this embodiment, the lens 13 is made from glass with refractive indexN_(d2) of 1.582 and Abbe number V_(d2) of 61.7. The light isconcentrated by the lens 13 to form an elliptic distribution pattern,64° in the X direction, 36° in the Y direction and the luminous fluxβ=69.816 lm at infinity (100× f_(s)) without consideration of airrefraction and scattering. The following values satisfy the equation(1), equation (2), equation (3) and equation (7):

η = 0.8893 I_(1/2) = 30.0 φ_(x) = 32.1 φ_(y) = 18.1$\frac{f_{s}}{r_{n}} = 1.0081$${\left( {N_{d\; 2} - 1} \right)\frac{d_{2}}{f_{s}}} = 0.4601$${\sqrt{\left( \frac{\varphi_{x} - \omega_{x}}{\pi} \right)^{2} + \left( \frac{\varphi_{y} - \omega_{y}}{\pi} \right)^{2}} \cdot f_{g}} = 0.2108$$\frac{E_{1/2}}{E_{d}} = 0.3406$

By the above table five and table six as well as FIG. 14, it has beenproved that the LED assembly with plano-Fresnel LED lens of theinvention can achieve higher efficiency and generate an ellipticdistribution pattern with uniform peak intensity so as to increase theapplication of the invention.

The Fourth Embodiment

Refer to FIG. 6 & FIG. 15.

TABLE SEVEN f = 2.530 υ = 0 Surface No. R or R_(F) d_(i) Nd_(i) S0 ∞0.10 S1 ∞ 0.52 1.410 S2* 1.250 2.00 1.491 *Aspherical Zone Fesnel

TABLE EIGHT K A₂ A₄ A₆ Aspherical −1.0000E+00 0.0000E+00 0.0000E+000.0000E+00 Surface h_(d) r₁ r_(n) No. of Zone Fesnel Surface 0.06 0.3872.510 41 (mm)

In this embodiment, the lens 13 is made from PMMA plastic withrefractive index N_(d2) of 1.491 and Abbe number v_(d2) of 32. The lightis concentrated by the lens 13 to form an elliptic distribution pattern,68° in the X direction, 43° in the Y direction and the luminous fluxβ=72.48 lm at infinity (100× f_(s)) without consideration of airrefraction and scattering. The following values satisfy the equation(1), equation (2), equation (3) and equation (7).

η = 0.9233 I_(1/2) = 23.5 φ_(x) = 34.0 φ_(y) = 21.5$\frac{f_{s}}{r_{n}} = 1.0081$${\left( {N_{d\; 2} - 1} \right)\frac{d_{2}}{f_{s}}} = 0.3881$${\sqrt{\left( \frac{\varphi_{x} - \omega_{x}}{\pi} \right)^{2} + \left( \frac{\varphi_{y} - \omega_{y}}{\pi} \right)^{2}} \cdot f_{g}} = 0.1672$$\frac{E_{1/2}}{E_{d}} = 0.2231$

By the above table seven and table eight as well as FIG. 15, it has beenproved that the LED assembly with plano-Fresnel LED lens of theinvention can achieve higher efficiency and generate an ellipticdistribution pattern with uniform peak intensity so as to increase theapplication of the invention.

The Fifth Embodiment

Refer to FIG. 6 & FIG. 16

TABLE NINE fs = 5.061 υ = 0 Surface No. R or R_(F) d_(i) N_(di) S0 ∞0.10 S1 ∞ 0.52 1.410 S2* 2.500 2.00 1.582 *Spherical Zone Fesnel

TABLE TEN r_(t) r_(n) No. of Zone Fesnel Surface 0.0625 2.500 41 (mm)

In this embodiment, the lens 13 is made from glass with refractive indexN_(d2) of 1.582 and Abbe number v_(d2) of 61.7. The light isconcentrated by the lens 13 to form an elliptic distribution pattern 68°in the X direction, 43° in the Y direction and the luminous flux β=72.48lm at infinity (100× f_(s)) without consideration of air refraction andscattering. The following values satisfy the equation (1), equation (2),equation (3) and equation (7).

η = 0.8980 I_(1/2) = 22.5 φ_(x) = 43.0 φ_(y) = 34.5$\frac{f_{s}}{r_{n}} = 2.0243$${\left( {N_{d\; 2} - 1} \right)\frac{d_{2}}{f_{s}}} = 0.2300$${\sqrt{\left( \frac{\varphi_{x} - \omega_{x}}{\pi} \right)^{2} + \left( \frac{\varphi_{y} - \omega_{y}}{\pi} \right)^{2}} \cdot f_{g}} = 0.4536$$\frac{E_{1/2}}{E_{d}} = 0.1111$

By the above table nine and table ten as well as FIG. 16, it has beenproved that the LED assembly with plano-Fresnel LED lens of theinvention can achieve higher efficiency and generate an ellipticdistribution pattern with uniform peak intensity so as to increase theapplication of the invention.

The Sixth Embodiment

Refer to FIG. 6 & FIG. 17.

TABLE ELEVEN fs = 2.530 υ = 0 Surface No. R or R_(F) d_(i) N_(di) S0 ∞0.10 S1 ∞ 0.52 1.410 S2* 1.250 4.96 1.582 *Aspherical Zone Fesnel

TABLE TWELVE K A₂ A₄ A₆ Aspherical −9.0000E−01 0.0000E+00 2.4000E−055.7000E−08 Surface h_(d) r₁ r_(n) No. of Zone Fesnel Surface (mm) 0.060.387 2.478 46

In this embodiment, the lens 13 is made from glass with refractive indexNd2 of 1.582 and Abbe number vd2 of 61.7. The light is concentrated bythe lens 13 to form an elliptic distribution pattern 68° in the Xdirection, 43° in the Y direction and the luminous flux β=72.48 lm atinfinity (100× f_(s)) without consideration of air refraction andscattering. The following 15 values satisfy the equation (1), equation(2), equation (3) and equation (7).

η = 0.8913 I_(1/2) = 32.5 φ_(x) = 31.0 φ_(y) = 17.0$\frac{f_{s}}{r_{n}} = 1.0213$${\left( {N_{d\; 2} - 1} \right)\frac{d_{2}}{f_{s}}} = 1.1401$${\sqrt{\left( \frac{\varphi_{x} - \omega_{x}}{\pi} \right)^{2} + \left( \frac{\varphi_{y} - \omega_{y}}{\pi} \right)^{2}} \cdot f_{g}} = 0.1030$$\frac{E_{1/2}}{E_{d}} = 0.4161$

By the above table eleven and table twelve as well as FIG. 17, it hasbeen proved that the LED assembly with plano-Fresnel LED lens of theinvention can achieve higher efficiency and generate an ellipticdistribution pattern with uniform peak intensity so as to increase theapplication of the invention.

The Seventh Embodiment

Refer to FIG. 6 & FIG. 18.

TABLE THIRTEEN fs = 2.530 υ = 0 Surface No. R or R_(F) d_(i) N_(di) S0 ∞0.10 S1 ∞ 0.52 1.410 S2* 1.250 4.99 1.582 *Aspherical Zone Fesnel

TABLE FOURTEEN K A₂ A₄ A₆ Aspherical −1.1000E+00 0.0000E+00 2.4000E−055.7000E−08 Surface h_(d) r₁ r_(n) No. of Zone Fesnel Surface (mm) 0.060.388 2.494 38

In this embodiment, the lens 13 is made from glass with refractive indexN_(d2) of 1.582 and Abbe number v_(d2) of 61.7. The light isconcentrated by the lens 13 to form an elliptic distribution pattern,65° in the X direction, 40° in the Y direction and the luminous fluxβ=69.33 lm at infinity (100× f_(s)) without consideration of airrefraction and scattering. The following values satisfy the equation(1), equation (2), equation (3) and equation (7).

η = 0.8832 I_(1/2) = 27.5 φ_(x) = 33.7 φ_(y) = 19.5$\frac{f_{s}}{r_{n}} = 1.0146$${\left( {N_{d\; 2} - 1} \right)\frac{d_{2}}{f_{s}}} = 1.1475$${\sqrt{\left( \frac{\varphi_{x} - \omega_{x}}{\pi} \right)^{2} + \left( \frac{\varphi_{y} - \omega_{y}}{\pi} \right)^{2}} \cdot f_{g}} = 0.1252$$\frac{E_{1/2}}{E_{d}} = 0.2799$

By the above table thirteen and table fourteen as well as FIG. 18, ithas been proved that the LED assembly with plano-Fresnel LED lens of theinvention can achieve higher efficiency and generate an ellipticdistribution pattern with uniform peak intensity so as to increase theapplication of the invention.

The Eighth Embodiment

Refer to FIG. 6 & FIG. 19.

TABLE FIFTEEN fs = 2.530 υ = 3.505 Surface No. R or R_(F) d_(i) N_(di)S0 ∞ 0.10 S1 ∞ 0.52 1.410 S2* 1.250 2.00 1.582 *Aspherical Zone Fesnel

TABLE SIXTEEN K A₂ A₄ A₆ Aspherical −1.0000E+00 0.0000E+00 0.0000E+000.0000E+00 Surface h_(d) r₁ r_(n) No. of Zone Fesnel Surface (mm) 0.060.387 2.387 37

In this embodiment, the lens 13 is made from glass with refractive indexN_(d2) of 1.582 and Abbe number v_(d2) of 61.7. The light isconcentrated by the lens 13 to form an elliptic distribution pattern,65° in the X direction, 60° in the Y direction and the luminous fluxβ=69.588 lm at infinity (100× f_(s)) without consideration of airrefraction and scattering. The following values satisfy the equation(1), equation (2), equation (3) and equation (7).

η = 0.8976 I_(1/2) = 22.0 φ_(x) = 37.5 φ_(y) = 27.0$\frac{f_{s}}{r_{n}} = 1.0598$${\left( {N_{d\; 2} - 1} \right)\frac{d_{2}}{f_{s}}} = 0.4601$${\sqrt{\left( \frac{\varphi_{x} - \omega_{x}}{\pi} \right)^{2} + \left( \frac{\varphi_{y} - \omega_{y}}{\pi} \right)^{2}} \cdot f_{g}} = 0.2176$$\frac{E_{1/2}}{E_{d}} = 0.3022$

By the above table fifteen and table sixteen as well as FIG. 19, it hasbeen proved that the LED assembly with plano-Fresnel LED lens of theinvention can achieve higher efficiency and generate an ellipticdistribution pattern with uniform peak intensity so as to increase theapplication of the invention.

The Ninth Embodiment

Refer to FIG. 6 & FIG. 20.

TABLE SEVENTEEN fs = 2.530 υ = 7.172 Surface No. R or R_(F) d_(i) N_(di)S0 ∞ 0.10 S1 ∞ 0.52 1.410 S2* 1.250 2.00 1.582 *Aspherical Zone Fesnel

TABLE EIGHTEEN K A₂ A₄ A₆ Aspherical −1.0000E+00 0.0000E+00 0.0000E+000.0000E+00 Surface h_(d) r₁ r_(n) No. of Zone Fesnel Surface (mm) 0.060.387 2.258 33

In this embodiment, the lens 13 is made from glass with refractive indexN_(d2) of 1.582 and Abbe number v_(d2) of 61.7. The light isconcentrated by the lens 13 to form an elliptic distribution pattern,68° in the X direction, 33° in the Y direction and the luminous fluxβ=71.267 lm at infinity (100× f_(s)) without consideration of airrefraction and scattering. The following values satisfy the equation(1), equation (2), equation (3) and equation (7).

η = 0.9078 I_(1/2) = 34.0 φ_(x) = 33.8 φ_(y) = 16.8$\frac{f_{s}}{r_{n}} = 1.2045$${\left( {N_{d\; 2} - 1} \right)\frac{d_{2}}{f_{s}}} = 0.4601$${\sqrt{\left( \frac{\varphi_{x} - \omega_{x}}{\pi} \right)^{2} + \left( \frac{\varphi_{y} - \omega_{y}}{\pi} \right)^{2}} \cdot f_{g}} = 0.2176$$\frac{E_{1/2}}{E_{d}} = 0.4998$

By the above table seventeen and table eighteen as well as FIG. 20, ithas been proved that the LED assembly with plano-Fresnel LED lens of theinvention can achieve higher efficiency and generate an ellipticdistribution pattern with uniform peak intensity so as to increase theapplication of the invention.

The Tenth Embodiment

Refer to FIG. 6 & FIG. 21.

TABLE NINETEEN fs = 2.530 υ = 0 Surface No. R or R_(F) d_(i) N_(di) S0 ∞0.10 S1 ∞ 0.52 1.410 S2* 1.250 2.00 1.582 *Aspherical Zone Fesnel

TABLE TWENTY K A₂ A₄ A₆ Aspherical −1.0000E+00 0.0000E+00 0.0000E+000.0000E+00 Surface r_(t) r_(n) No. of Zone Fesnel Surface (mm) 0.5 2.5005

In this embodiment, the lens 13 is made from glass with refractive indexN_(d2) of 1.582 and Abbe number v_(d2) of 61.7. The light isconcentrated by the lens 13 to form an elliptic distribution pattern,68° in the X direction, 70° in the Y direction and the luminous fluxβ=72.056 lm at infinity (100× f_(s)) without consideration of airrefraction and scattering. The following values satisfy the equation(1), equation (2), equation (3) and equation (7).

η = 0.9214 I_(1/2) = 26.0 φ_(x) = 40.5 φ_(y) = 35.0$\frac{f_{s}}{r_{n}} = 1.0121$${\left( {N_{d\; 2} - 1} \right)\frac{d_{2}}{f_{s}}} = 0.4601$${\sqrt{\left( \frac{\varphi_{x} - \omega_{x}}{\pi} \right)^{2} + \left( \frac{\varphi_{y} - \omega_{y}}{\pi} \right)^{2}} \cdot f_{g}} = 0.0081$$\frac{E_{1/2}}{E_{d}} = 0.1366$

By the above table nineteen and table twenty as well as FIG. 21, it hasbeen proved that the LED assembly with plano-Fresnel LED lens of theinvention can achieve higher efficiency and generate an ellipticdistribution pattern with uniform peak intensity so as to increase theapplication of the invention.

The Eleventh Embodiment

Refer to FIG. 6 & FIG. 22.

TABLE TWENTY-ONE fs = 2.530 υ = 0 Surface No. R or R_(F) d_(i) N_(di) S0∞ 0.10 S1 ∞ 0.52 1.410 S2* 1.250 2.00 1.582 *Aspherical Zone Fesnel

TABLE TWENTY-TWO K A₂ A₄ A₆ Aspherical −1.0000E+00 0.0000E+00 0.0000E+000.0000E+00 Surface r_(t) r_(n) No. of Zone Fesnel Surface (mm) 0.06252.500 40

In this embodiment, the lens 13 is made from glass with refractive indexN_(d2) of 1.582 and Abbe number v_(d2) of 61.7. The light isconcentrated by the lens 13 to form an elliptic distribution pattern,60° in the X direction, 80° in the Y direction and the luminous fluxβ=72.164 lm at infinity (100× f_(s)) without consideration of airrefraction and scattering. The following values satisfy the equation(1), equation (2), equation (3) and equation (7).

η = 0.9192 I_(1/2) = 30.0 φ_(x) = 39.4 φ_(y) = 30$\frac{f_{s}}{r_{n}} = 1.0121$${\left( {N_{d\; 2} - 1} \right)\frac{d_{2}}{f_{s}}} = 0.4601$${\sqrt{\left( \frac{\varphi_{x} - \omega_{x}}{\pi} \right)^{2} + \left( \frac{\varphi_{y} - \omega_{y}}{\pi} \right)^{2}} \cdot f_{g}} = 0.1147$$\frac{E_{1/2}}{E_{d}} = 0.2184$

By the above table twenty-one and table twenty-two as well as FIG. 22,it has been proved that the LED assembly with plano-Fresnel LED lens ofthe invention can achieve higher efficiency and generate an ellipticdistribution pattern with uniform peak intensity so as to increase theapplication of the invention.

The Twelfth Embodiment

Refer to FIG. 6 & FIG. 23.

TABLE TWENTY-THREE fs = 2.530 υ = 0 Surface No. R or R_(F) d_(i) N_(di)S0 ∞ 0.10 S1 30.00 0.62 1.410 S2* 1.250 1.90 1.582 *Aspherical ZoneFesnel

TABLE TWENTY-FOUR K A₂ A₄ A₆ Aspherical −1.0000E+00 0.0000E+000.0000E+00 0.0000E+00 Surface h_(d) r₁ r_(n) No. of Zone Fesnel Surface(mm) 0.06 0.387 2.510 42

In this embodiment, the lens 13 is made from glass with refractive indexN_(d2) of 1.582 and Abbe number v_(d2) of 61.7. The light isconcentrated by the lens 13 to form an elliptic distribution pattern,60° in the X direction, 40° in the Y direction and the luminous fluxβ=69.506 lm at infinity (100× f_(s)) without consideration of airrefraction and scattering. The following values satisfy the equation(1), equation (2), equation (3) and equation (7).

η = 0.8854 I_(1/2) = 30.0 φ_(x) = 33.1 φ_(y) = 19.0$\frac{f_{s}}{r_{n}} = 1.0008$${\left( {N_{d\; 2} - 1} \right)\frac{d_{2}}{f_{s}}} = 0.4361$${\sqrt{\left( \frac{\varphi_{x} - \omega_{x}}{\pi} \right)^{2} + \left( \frac{\varphi_{y} - \omega_{y}}{\pi} \right)^{2}} \cdot f_{g}} = 0.2053$$\frac{E_{1/2}}{E_{d}} = 0.2188$

By the above table twenty-three and table twenty-four as well as FIG.23, it has been proved that the LED assembly with plano-Fresnel LED lensof the invention can achieve higher efficiency and generate an ellipticdistribution pattern with uniform peak intensity so as to increase theapplication of the invention.

The Thirteenth Embodiment

Refer to FIG. 6 & FIG. 24.

TABLE TWENTY-FIVE fs = 2.530 υ = 0 Surface No. R or R_(F) d_(i) N_(di)S0 ∞ 0.10 S1 9.00 0.87 1.410 S2* 1.250 1.65 1.582 *Aspherical ZoneFesnel

TABLE TWENTY-SIX K A₂ A₄ A₆ Aspherical −1.0000E+00 0.0000E+00 0.0000E+000.0000E+00 Surface h_(d) r₁ r_(n) No. of Zone Fesnel Surface (mm) 0.060.387 2.510 35

In this embodiment, the lens 13 is made from glass with refractive indexN_(d2) of 1.582 and Abbe number v_(d2) of 61.7. The light isconcentrated by the lens 13 to form an elliptic distribution pattern,60° in the X direction, 40° in the Y direction and the luminous fluxβ=69.506 lm at infinity (100× f_(s)) without consideration of airrefraction and scattering. The following values satisfy the equation(1), equation (2), equation (3) and equation (7).

η = 0.8828 I_(1/2) = 29.0 φ_(x) = 31.0 φ_(y) = 20.2$\frac{f_{s}}{r_{n}} = 1.0081$${\left( {N_{d\; 2} - 1} \right)\frac{d_{2}}{f_{s}}} = 0.3786$${\sqrt{\left( \frac{\varphi_{x} - \omega_{x}}{\pi} \right)^{2} + \left( \frac{\varphi_{y} - \omega_{y}}{\pi} \right)^{2}} \cdot f_{g}} = 0.2227$$\frac{E_{1/2}}{E_{d}} = 0.2103$

By the above table twenty-five and table twenty-six as well as FIG. 24,it has been proved that the LED assembly with plano-Fresnel LED lens ofthe invention can achieve higher efficiency and generate an ellipticdistribution pattern with uniform peak intensity so as to increase theapplication of the invention.

1. A plano-Fresnel LED (Light emitting diode) lens, applied to a LEDassembly having a LED chip, a gel layer and a lens along a central axisfrom a source side to a forward side, comprising: an optical surface onthe forward side and an optical surface on the source side; wherein theoptical surface on forward side is a plano-Fresnel optical surface withvertical draft so as to make light from the LED chip pass through thegel layer, the lens and form an elliptic distribution pattern on theforward side, and the lens satisfies conditions of:$0.7 \leq \frac{f_{s}}{r_{n}} \leq 2.2$$0.1 \leq {\left( {N_{d\; 2} - 1} \right)\frac{d_{2}}{f_{s}}} \leq 1.25$wherein f_(s) is effective focal length, r_(n) is radius of a last zoneof a Fresnel optical surface, d₂ is thickness of the lens on a centralaxis, and N_(d2) is refractive index of the lens.
 2. The plano-FresnelLED lens as claimed in claim 1, wherein the lens further satisfiesfollowing conditions:${\sqrt{\left( \frac{\varphi_{x} - \omega_{x}}{\pi} \right)^{2} + \left( \frac{\varphi_{y} - \omega_{y}}{\pi} \right)^{2}} \cdot f_{g}} \leq 0.6$wherein:$f_{g} = {{\left( {\frac{1}{R_{1}} - \frac{1}{R_{F}}} \right) \cdot f_{s}}}$$\omega_{x} = {\tan^{- 1}\left( \frac{D}{{d\; 0} + {d\; 1} + {d\; 2} + {Lx}} \right)}$$\omega_{y} = {\tan^{- 1}\left( \frac{D}{{d\; 0} + {d\; 1} + {d\; 2} + {Ly}} \right)}$wherein f_(s) is effective focal length of the lens, 2φ_(x) (deg.) is anangle of a half of highest light intensity (I_(1/2)) in the X directionof the light emitted from the lens, 2φ_(y) (deg.) is an angle of a halfof highest light intensity (I_(1/2)) in the Y direction of the lightemitted from the lens, 2Lx is length of the LED chip in the X direction,2Ly is length of the LED chip in the Y direction, fg is a relative focallength of the lens, R₁ is a radius of an optical surface on the sourceside, R_(F) is a radius of a fresnel convex surface on the forward side,d₀ is thickness of the LED chip, d₁ is thickness of a gel layer on thecentral axis, d₂ is thickness of the lens on a central axis, D is radiusof an optical surface on the forward side.
 3. The plano-Fresnel LED lensas claimed in claim 1, wherein the optical surface on the source side isa flat surface or a concave surface.
 4. The plano-Fresnel LED lens asclaimed in claim 1, wherein the Fresnel optical surface is with equalzone height or with equal zone pitch.
 5. The plano-Fresnel LED lens asclaimed in claim 1, wherein an outer surface of the lens is with taper.6. The plano-Fresnel LED lens as claimed in claim 1, wherein the lens ismade from glass optical material or plastic optical material.
 7. A LEDassembly along a central axis from a source side to a forward sidecomprising: a LED chip, a gel layer and a plano-Fresnel LED lens ofclaim 1; wherein the LED assembly generates an elliptic distributionpattern and satisfies conditions of: E_(1/2) ≤ 0.6E_(d);${{{wherein}\mspace{14mu} E_{1/2}} = {\frac{I_{1/2}}{\left( {\pi \; {r_{n} \cdot \sin}\; \varphi_{x}} \right) \cdot \left( {{r_{n} \cdot \sin}\; \varphi_{y}} \right)} \cdot \eta}};$wherein r_(n) is radius of a last zone of the Fresnel optical surface,2φ_(x) (deg.) is an angle of a half of highest light intensity (I_(1/2))in the X direction of the light emitted from the lens, 2φ_(y) (deg.) isan angle of a half of highest light intensity (I_(1/2) ) in the Ydirection of the light emitted from the lens α is luminous flux of lightemitted from the LED chip, β is luminous flux of light at infinity (100×f_(s)) on the forward side without consideration of attenuation, η isratio of the luminous flux-η=β/α, E_(d) is illumination of the LED chip.8. The LED assembly as claimed in claim 7, wherein the ratio of luminousflux of light emitted from the LED chip to luminous flux of light atinfinity on the forward side satisfies:β/α≧85% wherein α is luminous flux of light emitted from the LED chip,and β is the luminous flux of light at infinity on the forward side ofthe LED assembly, neglecting air refraction and scattering.